Garry said:
What experiences have MINI owners had with the different octanes for petrol?
Does the higher octane 97 RON improve performance and fuel economy?
Can you run Shell Optimax 100 RON in the MINI?
Which brand of petrol is 'best' or doesn't that matter?

Standard unleaded is fine, but given that I only get about 8 gallons per fill, the extra GBP1.50 for Optimax is so little I nearly always fill with it....
It's supposed to clean your valves too. I intend on doing a 1 in 3 of Optimax at the very least, just in case it really goes keep the valves clean, and just in case that makes some sort of difference
I find my car starts better and is smoother at low revs with Optimax. There is a very marginal improvement in performance too.
One of the other threads suggested the diff. would be greater in hotter countries/summer time because detonation is less likely to occur with higher Octane fuel, so the ECU would be able to advance the timing that bit more, relative to 97RON. Roll on Summer - Now where's that sunroof switch gone
Incidentally what's that horrid 91RON stuff that comes as the standard fuel in N.Z... Total pants! It should be relegated to use by moped riders and dumper trucks!